1. Field of Invention
This invention provides an electrical barrier that controls snails, slugs, and similar gastropod mollusks in their movement from one location to another whereby they can be prohibited from entering into selected areas.
2. Description of Prior Art
This invention is especially useful in the garden to keep snails, slugs and similar gastropod mollusks from attacking plants of value. Heretofore the gardener relied primarily on the use of poisons to control these pests. Poisons are potentially dangerous to people, animals, birds and the ecological environment in general. In search of a better way to contrtol these pests, electrical methods have been proposed in recent years. Three such approaches are disclosed in three patents: Swiss patent No. 443,773 granted to Infanger on Feb. 15, 1968, U.S. Pat. No. 4,118,752 granted to Iguchi on Oct. 3, 1978 and German patent No. 3303077 granted to Bohm on Aug. 2, 1984. Infanger, in his patent, places a pair of horizontally spaced narrow conductors, like wires, around the area to be protected. He sends an electrical impulse throught the conductors timed to catch the snail as it bridges the two conductors and thereby kill the snail. This method requires the use of precisely spaced conductors, complex pulsing circuitry, a high current power source and a complex relationship between the conductor spacing, the snail size and the pulse timing. Iguchi, in his patent, places a pair of narrow, parallel exposed metal conductors, like wires, around the inside of an enclosure. He puts a snail bait inside the enclosed area and sends an electrical impulse through the conductors timed to catch the snail bridging the two conductors as the snail attempts to leave the enclosure, thus making the snail contract and fall back into the enclosure and get trapped. This method also requires the use of precisely spaced conductors, complex pulsing circuitry, relatively high power supply current and a complex relationship between the conductor spacing, the snail size and the pulse timing. Since this method is a trap, it relies upon attracting the snails into an area to get rid of them as opposed to controlling the snails movement by enclosing areas to be protected. Bohm, in his patent, like Infanger and Iguchi, relies upon two narrow horizontally spaced conductors, such as wires. The spacing between the conductors is critical since, if the spacing is too close, a large snail can step over the two conductors and, if the spacing is too wide, a small snail can travel over the first wire before contacting the second wire. Critical conductor spacing, complex pulse circuitry, high power supply current and critical timing requirements are disadvantages that increase the complexity, reduce the effectiveness and limit the usefulness of the electrical snail and slug control approaches available to date.